.net – RIA Services versus WCF services: what is a difference

netsilverlightwcfwcf-ria-services

There are a lot of information how to build Silverlight application using .NET RIA services, but it isn't clear what is unique thing in RIA that is absent in WCF?

Here are few topics that are talking around this topic: [1], [2]

But they doesn't give an answer to the question.

Sorry for the stupid question, but what does RIA Services layer bring into your app if you already have Silverlight <--> WCF Service <--> Business Logic <--> Entity Framework Model <--> Database? Authentication? Validation? Is it relly asset for you?

At the moment the only thing I see: with RIA services usage you don't need to host WCF service manually and don't need to configure any references on the client side (clien side == Silverlight application).

Probably I don't know some very useful features of the RIA Services? So could you please point me to the good doc for that?

Many thanks.

P.S. I've read a lot of different articles about differences, but can't clarify it… all articles "tell around" and aren't concrete. If you are going to give me a link to additional article, could you please be so kind and provide a list of benefits that YOU see.

Best Answer

Actually, you can use the same validation and authentication without using RIA Services. What RIA Services gives you is code generation. It creates your classes for you. You only need to put the business logic. I think RIA Services is very useful for developing small to mid apps very rapidly.

Another difference is that it hides the asynchronous calls to the web service. Many people don't like the async model (which is the only one you can use in Silverlight) and RIA services handles that for you.

I recommend reading this article from Shawn Wildermuth where he points out the pros and cons from both approaches and also includes ADO.NET data services (which is now called WCF Data Services, I think):

http://wildermuth.com/2009/09/29/Choosing_a_Data_Access_Layer_for_Silverlight_3

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

C# – the difference between const and readonly in C#

Apart from the apparent difference of

having to declare the value at the time of a definition for a const VS readonly values can be computed dynamically but need to be assigned before the constructor exits.. after that it is frozen.
const's are implicitly static. You use a ClassName.ConstantName notation to access them.

There is a subtle difference. Consider a class defined in AssemblyA.

public class Const_V_Readonly
{
  public const int I_CONST_VALUE = 2;
  public readonly int I_RO_VALUE;
  public Const_V_Readonly()
  {
     I_RO_VALUE = 3;
  }
}

AssemblyB references AssemblyA and uses these values in code. When this is compiled:

in the case of the const value, it is like a find-replace. The value 2 is 'baked into' the AssemblyB's IL. This means that if tomorrow I update I_CONST_VALUE to 20, AssemblyB would still have 2 till I recompile it.
in the case of the readonly value, it is like a ref to a memory location. The value is not baked into AssemblyB's IL. This means that if the memory location is updated, AssemblyB gets the new value without recompilation. So if I_RO_VALUE is updated to 30, you only need to build AssemblyA and all clients do not need to be recompiled.

So if you are confident that the value of the constant won't change, use a const.

public const int CM_IN_A_METER = 100;

But if you have a constant that may change (e.g. w.r.t. precision).. or when in doubt, use a readonly.

public readonly float PI = 3.14;

Update: Aku needs to get a mention because he pointed this out first. Also I need to plug where I learned this: Effective C# - Bill Wagner

Best Answer

Related Solutions

C# – the difference between String and string in C#

This is the style that Microsoft tends to use in their examples.

C# – the difference between const and readonly in C#

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